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Skinner MF, Delezene LK, Skinner MM, Mahoney P. Linear enamel hypoplasia in Homo naledi reappraised in light of new Retzius periodicities. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 184:e24927. [PMID: 38433613 DOI: 10.1002/ajpa.24927] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 02/07/2024] [Accepted: 02/14/2024] [Indexed: 03/05/2024]
Abstract
OBJECTIVES Among low-latitude apes, developmental defects of enamel often recur twice yearly, linkable to environmental cycles. Surprisingly, teeth of Homo naledi from Rising Star in South Africa (241-335 kya), a higher latitude site with today a single rainy season, also exhibit bimodally distributed hypoplastic enamel defects, but with uncertain timing and etiology. Newly determined Retzius periodicities for enamel formation in this taxon enable a reconstruction of the temporal patterning of childhood stress. METHODS Using high resolution casts of 31 isolated anterior teeth from H. naledi, 82 enamel defects (linear enamel hypoplasia [LEH]) were identified. Seventeen teeth are assigned to three individuals. Perikymata in the occlusal wall of enamel furrows and between the onsets of successive LEH were visualized with scanning electron microscopy and counted. Defects were measured with an optical scanner. Conversion of perikymata counts to estimates of LEH duration and inter-LEH interval draws upon Retzius periodicities of 9 and 11 days. RESULTS Anterior teeth record more than a year of developmental distress, expressed as two asymmetric intervals centered on 4.5 and 7.5 months bounded by three LEH. Durations, also, show bimodal distributions, lasting 3 or 12 weeks. Short duration LEH are more severe than long duration. Relative incisor/canine rates of formation are indistinguishable from modern humans. DISCUSSION We invoke a disease and dearth model, with short episodes of distress reflecting onset of disease in young infants, lasting about 3 weeks, followed by a season of undernutrition, possibly intensified by secondary plant compounds, spanning about 12 weeks, inferably coincident with austral winter.
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Affiliation(s)
- Mark Fretson Skinner
- Department of Archaeology, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Lucas Kyle Delezene
- Department of Anthropology, University of Arkansas, Fayetteville, Arkansas, USA
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
| | - Matthew M Skinner
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
| | - Patrick Mahoney
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
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Mahoney P, McFarlane G, Taurozzi AJ, Madupe PP, O'Hara MC, Molopyane K, Cappellini E, Hawks J, Skinner MM, Berger L. Human-like enamel growth in Homo naledi. AMERICAN JOURNAL OF BIOLOGICAL ANTHROPOLOGY 2024; 184:e24893. [PMID: 38180115 DOI: 10.1002/ajpa.24893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2023] [Revised: 11/12/2023] [Accepted: 12/14/2023] [Indexed: 01/06/2024]
Abstract
OBJECTIVES A modern pattern (rate and duration) of dental development occurs relatively recently during human evolution. Given the temporal overlap of Homo naledi with the first appearance of fossil Homo sapiens in Africa, this small-bodied and small-brained hominin presents an opportunity to elucidate the evolution of enamel growth in the hominin clade. Here we conduct the first histological study of two permanent mandibular canines and one permanent maxillary first molar, representing three individuals attributed to H. naledi. We reconstruct the rate and duration of enamel growth and compare these findings to those reported for other fossil hominins and recent humans. MATERIALS AND METHODS Thin sections of each tooth were produced using standard histological methods. Daily and longer period incremental markings were measured to reconstruct enamel secretion and extension rates, Retzius periodicity, canine crown and molar cusp formation time. RESULTS Daily enamel secretion rates overlapped with those from recent hominins. Canine crown formation time is similar to that observed in recent Europeans but is longer than canine formation times reported for most other hominins including Australopithecus and H. neanderthalensis. The extended period of canine formation appears to be due to a relatively tall enamel crown and a sustained slow rate of enamel extension in the cervical portion of the crown. A Retzius periodicity of 11 days for the canines, and nine days for the molar, in H. naledi parallel results found in recent humans. An 11-day periodicity has not been reported for Late Pleistocene Homo (H. erectus, H. neanderthalensis) and is rarely found in Australopithecus and Paranthropus species. DISCUSSION Enamel growth of H. naledi is most similar to recent humans though comparative data are limited for most fossil hominin species. The high Retzius periodicity values do not follow expectations for a small-brained hominin.
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Affiliation(s)
- Patrick Mahoney
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Gina McFarlane
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Alberto J Taurozzi
- Section for GeoGenetics, Globe Institute, University of Copenhagen, Copenhagen, Denmark
| | - Palesa P Madupe
- Section for GeoGenetics, Globe Institute, University of Copenhagen, Copenhagen, Denmark
- Human Evolution Research Institute, University of Cape Town, Rondebosch, South Africa
| | - Mackie C O'Hara
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Keneiloe Molopyane
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
- The National Geographic Society, Washington, District of Columbia, USA
| | - Enrico Cappellini
- Section for GeoGenetics, Globe Institute, University of Copenhagen, Copenhagen, Denmark
| | - John Hawks
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
- Department of Anthropology, University of Wisconsin-Madison, USA
| | - Matthew M Skinner
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Lee Berger
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
- The National Geographic Society, Washington, District of Columbia, USA
- The Carnegie Institution for Science, Washington, District of Columbia, USA
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Delezene LK, Scott JE, Irish JD, Villaseñor A, Skinner MM, Hawks J, Berger LR. Sex-biased sampling may influence Homo naledi tooth size variation. J Hum Evol 2024; 187:103490. [PMID: 38266614 DOI: 10.1016/j.jhevol.2023.103490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2023] [Revised: 12/20/2023] [Accepted: 12/21/2023] [Indexed: 01/26/2024]
Abstract
A frequent source of debate in paleoanthropology concerns the taxonomic unity of fossil assemblages, with many hominin samples exhibiting elevated levels of variation that can be interpreted as indicating the presence of multiple species. By contrast, the large assemblage of hominin fossils from the Rising Star cave system, assigned to Homo naledi, exhibits a remarkably low degree of variation for most skeletal elements. Many factors can contribute to low sample variation, including genetic drift, strong natural selection, biased sex ratios, and sampling of closely related individuals. In this study, we tested for potential sex-biased sampling in the Rising Star dental sample. We compared coefficients of variation for the H. naledi teeth to those for eight extant hominoid samples. We used a resampling procedure that generated samples from the extant taxa that matched the sample size of the fossil sample for each possible Rising Star dental sex ratio. We found that variation at four H. naledi tooth positions-I2, M1, P4, M1-is so low that the possibility that one sex is represented by few or no individuals in the sample cannot be excluded. Additional evidence is needed to corroborate this inference, such as ancient DNA or enamel proteome data, and our study design does not address other potential factors that would account for low sample variation. Nevertheless, our results highlight the importance of considering the taphonomic history of a hominin assemblage and suggest that sex-biased sampling is a plausible explanation for the low level of phenotypic variation found in some aspects of the current H. naledi assemblage.
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Affiliation(s)
- Lucas K Delezene
- Department of Anthropology, University of Arkansas, Fayetteville, AR, 72701, USA; Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa.
| | - Jeremiah E Scott
- Department of Medical Anatomical Sciences, College of Osteopathic Medicine of the Pacific, Western University of Health Sciences, Pomona, CA, 91766, USA
| | - Joel D Irish
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa; School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, L3 3AF, UK
| | - Amelia Villaseñor
- Department of Anthropology, University of Arkansas, Fayetteville, AR, 72701, USA
| | - Matthew M Skinner
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa; Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103, Leipzig, Germany
| | - John Hawks
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa; Department of Anthropology, University of Wisconsin-Madison. Madison, WI, 53706, USA
| | - Lee R Berger
- Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Private Bag 3, WITS, 2050, South Africa; National Geographic Society, 1145 17th Street NW, Washington DC, 20036, USA
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Brophy JK, Bolter DR, Elliott M, Hawks J, Berger LR. An examination of Homo naledi early juveniles recovered from the Rising Star cave system, South Africa. Ann Hum Biol 2024; 51:2321128. [PMID: 38509686 DOI: 10.1080/03014460.2024.2321128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2023] [Accepted: 02/06/2024] [Indexed: 03/22/2024]
Abstract
BACKGROUND Six Homo naledi early juveniles were recovered from U.W. 101 (Dinaledi Chamber), U.W. 102 (Lesedi Chamber), and U.W. 110 in the Rising Star cave system. AIM This paper develops the information for the H. naledi early juvenile life stage, as defined by a combination of deciduous and permanent dentition, and the eruption of the first permanent molar. SUBJECTS AND METHODS The growing number of young individuals recovered from the Rising Star cave system allows us to gain a better understanding of their variation, or lack thereof, and provides a basis to estimate broad ranges for age at death of the individuals. The individuals are identified and described through craniodental remains and spatial associations. RESULTS AND CONCLUSION Our results show that the teeth are remarkably consistent across the localities in their metric and non-metric traits, and our analyses refine previous estimations on dental eruptions with the first permanent molar erupting first in the sequence among permanent teeth.
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Affiliation(s)
- Juliet K Brophy
- Department of Geography and Anthropology, LA State University, Baton Rouge, LA, USA
- The Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
| | - Debra R Bolter
- The Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
- Department of Anthropology, Modesto Junior College, Modesto, CA, USA
- Department of Anthropology, CA State University Stanislaus, Turlock, CA, USA
| | - Marina Elliott
- The Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
- Department of Archaeology, Simon Fraser University, Burnaby, BC, Canada
| | - John Hawks
- The Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
- Department of Anthropology, University of WI-Madison, Madison, WI, USA
| | - Lee R Berger
- The Centre for the Exploration of the Deep Human Journey, University of the Witwatersrand, Johannesburg, South Africa
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Bolter DR, Cameron N, Hawks J, Churchill SE, Berger L, Bernstein R, Boughner JC, Elton S, Leece AB, Mahoney P, Molopyane K, Monson TA, Pruetz J, Schell L, Stull KE, Wolfe CA. Addressing the growing fossil record of subadult hominins by reaching across disciplines. Evol Anthropol 2023; 32:180-184. [PMID: 37555538 DOI: 10.1002/evan.21995] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Accepted: 07/03/2023] [Indexed: 08/10/2023]
Affiliation(s)
- Debra R Bolter
- Department of Anthropology, Modesto Junior College, Modesto, California, USA
- Faculty of Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Department of Anthropology, California State University Stanislaus, Turlock, California, USA
| | - Noel Cameron
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, Leicestershire, UK
| | - John Hawks
- Faculty of Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Anthropology Department, University of Wisconsin, Madison, Wisconsin, USA
| | - Steven E Churchill
- Department of Evolutionary Anthropology, Duke University, Durham, North Carolina, USA
| | - Lee Berger
- Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Department of Explorer in Residence, National Geographic Society, Washington, District of Columbia, USA
| | - Robin Bernstein
- Department of Anthropology, University of Colorado at Boulder, Boulder, Colorado, USA
| | - Julia C Boughner
- Department of Anatomy, Physiology and Pharmacology, University of the Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Sarah Elton
- Faculty of Social Sciences and Health, Durham University, Durham, UK
| | - A B Leece
- Palaeoscience, Department of Archaeology and History, LaTrobe University, Melbourne, Victoria, Australia
- Geoarchaeology and Archaeometry Research Group, Faculty of Science and Engineering, Southern Cross University, Lismore, New South Wales, Australia
| | - Patrick Mahoney
- Skeletal Biology Research Centre, School of Anthropology and Conservation, University of Kent, Canterbury, UK
| | - Keneiloe Molopyane
- Faculty of Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Tesla A Monson
- Department of Anthropology, Western Washington University, Bellingham, Washington, USA
| | - Jill Pruetz
- Department of Anthropology, Texas State University San Marcos, San Marcos, Texas, USA
| | - Lawrence Schell
- Department of Anthropology, State University of New York, Albany, New York, USA
| | - Kyra E Stull
- Department of Anthropology, University of Reno, Reno, Nevada, USA
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Decrausaz SL, Cameron ME. A growth area: A review of the value of clinical studies of child growth for palaeopathology. Evol Med Public Health 2022; 10:108-122. [PMID: 35273803 PMCID: PMC8903130 DOI: 10.1093/emph/eoac005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 01/17/2022] [Indexed: 12/11/2022] Open
Abstract
Studies of living children demonstrate that early life stress impacts linear growth outcomes. Stresses affecting linear growth may also impact later life health outcomes, including increased cardiometabolic disease risk. Palaeopathologists also assess the growth of children recovered from bioarchaeological contexts. Early life stresses are inferred to affect linear growth outcomes, and measurements of skeletal linear dimensions alongside other bioarchaeological information may indicate the types of challenges faced by past groups. In clinical settings, the impacts of stress on growing children are typically measured by examining height. Palaeopathologists are limited to examining bone dimensions directly and must grapple with incomplete pictures of childhood experiences that may affect growth. Palaeopathologists may use clinical growth studies to inform observations among past children; however, there may be issues with this approach. Here, we review the relationship between contemporary and palaeopathological studies of child and adolescent growth. We identify approaches to help bridge the gap between palaeopathological and biomedical growth studies. We advocate for: the creation of bone-specific growth reference information using medical imaging and greater examination of limb proportions; the inclusion of children from different global regions and life circumstances in contemporary bone growth studies; and greater collaboration and dialogue between palaeopathologists and clinicians as new studies are designed to assess linear growth past and present. We advocate for building stronger bridges between these fields to improve interpretations of growth patterns across human history and to potentially improve interventions for children living and growing today.
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Affiliation(s)
- Sarah-Louise Decrausaz
- Department of Anthropology, University of Victoria, Cornett Building, Victoria, BC V8P 5C2, Canada
| | - Michelle E Cameron
- Department of Anthropology, University of Toronto, 19 Ursula Franklin Street, Toronto, ON M5S 2S2, Canada
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Turbón D, Rebato E, Salicrú M. Phenotypic diversity and history of the Congo Basin populations: Equatorial Guinea, Bantu Speaking Central Africans and African Pygmies. Ann Hum Biol 2021; 48:119-132. [PMID: 33821699 DOI: 10.1080/03014460.2021.1909136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
BACKGROUND African Pygmy Populations (APP) are believed to be one of the first groups of the Congo Basin rainforest peoples to separate from the rest of modern humanity. The arrival of Bantu speaking agriculturalists from 5,000 BP led to the formation of a large number of ethnic complexes in Central Africa and the Atlantic coastal area, mainly due to a one-way flow of pygmy women. There are now only a few small contingents of African Pygmy population groups who are mixed or who have almost disappeared as a result of migratory flows from Cameroon. AIMS We analysed the adult phenotypic diversity of 9 populations (17 groups of both sexes) of the Congo basin and Bioko Island, which were anthropometrically characterised in 1948. The phenotypic clusters that we detected, which we interpret as likely mixing of local Pygmy populations and Bantus, may be useful as references for future studies, particularly genetics. SUBJECTS AND METHODS The matrix of inter-distances between populations was generated, using the 21 variables, with the Euclidean distance between the mean vectors relating to the standardised variables. When the UPGMA (Unweighted Pair Group Method with Arithmetic Mean) was used separately in men and women, the phylogenetic trees showed a clear separation between populations. RESULTS The body measurements that most effectively distinguished the groups are linear dimensions and the width of the hips and mean thoracic circumference. In this study, the cephalo-facial dimensions were of little value in identifying the groups. CONCLUSIONS The samples of Equatorial Guinea show a major inter-group overlap, and considerable intra-group variations. There are also notable differences amongst African Pygmy populations in terms of height, but not in body proportions.
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Affiliation(s)
- Daniel Turbón
- Zoology and Anthropology Sub-Department of Evolutionary Biology, Ecology and Environmental Sciences, Faculty of Biology, University of Barcelona, Barcelona, Spain
| | - Esther Rebato
- Genetics, Physical Anthropology and Animal Physiology Department of Faculty of Science and Technology, University of the Basque Country-Euskal Herriko Unibertsitatea, (UPV/EHU), Bilbao, Spain
| | - Miquel Salicrú
- Statistics Sub-Department of Genetics, Microbiology and Statistics, Faculty of Biology, University of Barcelona, Barcelona, Spain
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